Hans One cannot conclude with certanty that the lower Tg material is the prepreg. Since the core has been through two lamination cycles (at the laminator and in your press) it is usual to infer that the lower Tg is the prepreg. This is reinforced by the single peak after heating. One material or the other was undercured after your lamination cycle. Did the second lab you mentioned heat the material after DSC as much as the first lab to complete the cure? If these data represent real boards I suggest a bake to fully cure them. Hard top be sure, these are thoughts which I hope will help Jerry Sallo Sallo Consulting Services ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################